The use of steering knuckles for carrying wheel assemblies is a long established practice for providing steerability to vehicle axles. As such, in addition to their use on various automobiles, steering knuckles are employed on a large number of light and heavy duty commercial trucks in use today, and are utilized with both permanent (fixed) and auxiliary, lift-type axles.
Steering knuckles of the known-type are generally constructed of upper and lower yoke arms carrying rigidly (e.g., immovably) mounted upper and lower bosses (each having an aperture for receipt of a kingpin), as well as a main body (joining the two yoke arms) having an integrated or press fit spindle extending centrally therefrom for mounting a wheel assembly thereon. In conventional steerable axle construction, the beam of the axle normally includes a kingpin mounted at each end thereof in a generally vertical orientation for assembly of a steering knuckle thereto. When assembled, the steering knuckle is positioned so that the kingpin ends ride in the apertures of the upper and lower bosses so that the knuckle can rotate back and forth about the axis of the kingpin to provide steerability. Although steering knuckles are widely used in the automotive arts, various drawbacks related to known knuckle designs as well as known methods of assembling such designs to axles have been discovered (e.g., principally related to component wear rates).
Specifically, in one example, because a kingpin is typically press-fit into an axle prior to assembly of a steering knuckle thereon, and because in conventional steering knuckle design, a knuckle is normally of one-piece construction, there is substantial skill required to assemble such a steering knuckle to a “kingpinned” axle (an axle having a kingpin pre-installed). Furthermore, maintenance or repair of a conventionally installed steering knuckle assembly of known type is difficult because of the complications inherent in removing a one-piece steering knuckle from a fixed kingpin. Moreover, because of differences in manufacturing tolerances as well as differences in axle and kingpin designs (which may, for example, come from different manufacturers), the initial “fit” of a steering knuckle on a individual axle is often imperfect and adjustments are, therefore, typically made to improve the installed fit in order to improve performance and/or wear characteristics.
For example, in a conventional steering knuckle and kingpin assembly, if there is a space between the bosses of the steering knuckle and the kingpin seating area of the axle (the area of the axle surrounding the kingpin), thus leaving a gap between the axle and the boss such as gap “G” in FIG. 4b, unwanted movement of the knuckle on the kingpin occurs during vehicle operation. More specifically, when such a gap between the knuckle bosses and the axle exists after assembly, the kingpin will, in effect, oscillate within the apertures of the bosses when a vehicle employing the axle is operated (due to movement of the knuckle relative to the kingpin, for example). This oscillation (i.e., a axial movement of the kingpin in and out of the boss apertures), in turn, creates alternating high and low pressure pockets within the boss apertures. As a result, a vacuum in the apertures is created which sucks dirt or other debris into the bosses, thereby causing wear to the kingpin as well as to the bearing and/or bushing surfaces located within the apertures of the bosses.
Several prior art attempts have been made to solve the above described problems associated with the failure to acceptably seat the steering knuckles and contacting parts in steerable axles, particularly in heavy duty vehicles such as trucks and trailers. One known prior art technique for addressing this problem involves eliminating undesired gaps in steering knuckle/axle assemblies by manually adding shims over the kingpin during knuckle installation. The shims which are added effectively eliminate unwanted space between the bosses and the kingpin seating area. As will be recognized, this prior art method of tailoring steering knuckle fit requires additional labor and parts, and further relies on a trial and error approach when attempting to, hopefully, end up with the appropriate/ideal distance between bosses and the axle (i.e., the assembler must guess at the correct number of shims which must be added to eliminate the “gap” and then adjust the number after a trial fit, if necessary).
More recent attempts to solve the above described and other problems in the steerable axle arts have involved the use of multi-piece knuckles employing bolt-on yokes or bosses such as exemplified by U.S. Pat. No. 6,367,825 (hereinafter the '825 patent). Nevertheless, although the '825 patent generally addresses the problem described herein, the range of adjustability which is achieved by the mechanism described in the '825 patent is finite (limited) because adjustment of the knuckle is restricted to the increments dictated by the size of the teeth of the boss and knuckle (flange) mating portions. More specifically, the boss can only be adjusted a distance which is a factor of the size of the mating teeth of the respective knuckle parts.
It is, of course, desirable to have the capability to adjust the position of a boss in a greater number of increments (e.g., a non-finite number) so as to create a more precise “fit” when assembling a steering knuckle to an axle. In short, such improved adjustability would provide the capability for more precisely fine tuning the fit of a steering knuckle on a steerable axle. This, in turn, would reduce part wear rates and decrease labor costs associated with axle assembly.
In view of the above, it is apparent that there exists a need in the art for methods and/or apparatus which overcome or, at least, ameliorate the above drawbacks. It is a purpose of this invention to fulfill this need, as well as other needs in the art which will become apparent to the skilled artisan once given the above disclosure.